Viser treff 1481-1500 av 2078

    • Hooded seal Cystophora cristata foraging areas in the Northeast Atlantic Ocean—Investigated using three complementary methods 

      Vacquie-Garcia, Jade; Lydersen, Christian; Biuw, Martin; Haug, Tore; Fedak, Michael A.; Kovacs, Kit M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-06)
      Identifying environmental characteristics that define the ecological niche of a species is essential to understanding how changes in physical conditions might affect its distribution and other aspects of its ecology. The present study used satellite relay data loggers (SRDLs) to study habitat use by Northeast Atlantic hooded seals (N = 20; 9 adult females, 3 adult males, and 8 juveniles). Three ...
    • Gene-centromere mapping in meiotic gynogenetic European seabass 

      Oral, Münevver; Colléter, Julie; Bekaert, Michaël; Taggart, John B.; Palaoikostas, Christos; McAndrew, Brendan J.; Vandeputte, Marc; Chatain, Béatrice; Kuhl, Heiner; Reinhardt, Richard; Peruzzi, Stefano; Penman, David J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-07)
      Background: <br> Fully isogenic lines in fish can be developed using “mitotic” gynogenesis (suppression of first zygotic mitosis following inactivation of the sperm genome). However, genome-wide verification of the steps in this process has seldom been applied. We used ddRADseq to generate SNP markers in a meiotic gynogenetic family of European seabass (Dicentrarchus labrax): (i) to verify the lack ...
    • Activity of xyloglucan endotransglucosylases/hydrolases suggests a role during host invasion by the parasitic plant Cuscuta reflexa 

      Olsen, Stian; Krause, Kirsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-27)
      The parasitic vines of the genus Cuscuta form haustoria that grow into other plants and connect with their vascular system, thus allowing the parasite to feed on its host. A major obstacle that meets the infection organ as it penetrates the host tissue is the rigid plant cell wall. In the present study, we examined the activity of xyloglucan endotransglucosylases/hydrolases (XTHs) during the ...
    • Transcriptome analysis identifies key metabolic changes in the hooded seal (Cystophora cristata) brain in response to hypoxia and reoxygenation 

      Hoff, Mariana Leivas Müller; Fabrizius, Andrej; Czech-Damal, Nicole U.; Folkow, Lars; Burmester, Thorsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-01-03)
      The brain of diving mammals tolerates low oxygen conditions better than the brain of most terrestrial mammals. Previously, it has been demonstrated that the neurons in brain slices of the hooded seal (Cystophora cristata) withstand hypoxia longer than those of mouse, and also tolerate reduced glucose supply and high lactate concentrations. This tolerance appears to be accompanied by a shift in the ...
    • Diving behaviour of Atlantic salmon at sea: effects of light regimes and temperature stratification 

      Hedger, Richard David; Rikardsen, Audun H.; Strøm, John Fredrik; Righton, David A.; Thorstad, Eva Bonsak; Næsje, Tor (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-04)
      The diving behaviour of adult Atlantic salmon Salmo salar L. post-spawners in the Norwegian and Barents Seas was monitored with pop-up satellite archival tags (PSATs) and data storage tags (DSTs). Salmon from the 3 studied populations showed similar depth use patterns: tagged specimens spent most of their time near the surface (mean of 82% of the time at depths <10 m), with occasional short deep ...
    • Climate warming enhances polar cod recruitment, at least transiently 

      Bouchard, Caroline; Geoffroy, Maxime; LeBlanc, Mathieu; Majewski, Andrew; Gauthier, Stéphane; Walkusz, Wojciech; Reist, James D.; Fortier, Louis (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-27)
      Polar cod (Boreogadus saida) is the dominant forage fish in Arctic seas and the main prey of the ringed seal (Pusa hispida), the beluga (Delphinapterus leucas) and several seabird species. Changes in the abundance of polar cod will have cascading effects on arctic marine ecosystems. We tested the hypothesis that an earlier sea ice breakup and warmer sea surface temperatures (SST) in spring-summer ...
    • The relative effects of farm management versus climate on lamb autumn weights 

      Pedersen, Elisabeth (Master thesis; Mastergradsoppgave, 2008-05-15)
      Abstract In this study I ask if farm management have such large effects on sheep (Ovis aries) production that climatic studies could be improved by taking it into account. The relative effects of climate and farm management on autumn live weights of lamb were studied in Troms, northern Norway. A mixed method approach was used, including analyses of multiple databases, as well as qualitative, ...
    • Estimating survival rate in Brünnich's guillemot (Uria lomvia) chicks. A study of mark-recapture methods using photo series data 

      Lorentzen, Erlend (Master thesis; Mastergradsoppgave, 2008-05)
      Three different mark-recapture models were applied to resighting data for Brünnich's guillemot (Uria lomvia) chicks obtained from photo series. Performances of the various models as potential tools for estimating chick survival over the breeding season were assessed. Of particular interest was Pradel’s multievent model, estimating state transition probabilities while accounting for uncertainty of ...
    • Winter behaviour of riverine anadromous Arctic charr and sea trout in northern Norway 

      Jensen, Jenny Lovisa Alexandra (Master thesis; Mastergradsoppgave, 2008-05)
      Based on earlier migration studies of lake-dwelling anadromous Arctic charr Salvelinus alpinus (L.) and sea trout Salmo trutta L. in northern Norway, both species are believed to solely overwinter in fresh water and spend only one to three months in the sea during summer. This is an assumption upon which all current management of the species in the area is based, although no studies have focused on ...
    • Vole abundance and reindeer carcasses determine breeding activity of Arctic foxes in low Arctic Yamal, Russia 

      Ehrich, Dorothee; Cerezo, Maite; Rodnikova, Anna Y.; Sokolova, Natalya A.; Fuglei, Eva; Shtro, Victor; Sokolov, Aleksandr A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-16)
      High latitude ecosystems are at present changing rapidly under the influence of climate warming, and specialized Arctic species at the southern margin of the Arctic may be particularly affected. The Arctic fox (Vulpes lagopus), a small mammalian predator endemic to northern tundra areas, is able to exploit different resources in the context of varying tundra ecosystems. Although generally widespread, ...
    • Regulation of gene expression is associated with tolerance of the Arctic copepod Calanus glacialis to CO2-acidified sea water 

      Bailey, Allison Michelle; De Wit, Pierre; Thor, Peter; Browman, Howard; Bjelland, Reidun Marie; Shema, Steven; Fields, David M.; Runge, Jeffrey A.; Thompson, Cameron; Hop, Haakon (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-08-02)
      Ocean acidification is the increase in seawater pCO2 due to the uptake of atmospheric anthropogenic CO2, with the largest changes predicted to occur in the Arctic seas. For some marine organisms, this change in pCO2, and associated decrease in pH, represents a climate change-related stressor. In this study, we investigated the gene expression patterns of nauplii of the Arctic copepod Calanus glacialis ...
    • Sea ice thermohaline dynamics and biogeochemistry in the Arctic Ocean: Empirical and model results 

      Duarte, Pedro; Meyer, Amelie; Olsen, Lasse Mork; Kauko, Hanna Maria; Assmy, Philipp; Rösel, Anja; Itkin, Polona; Hudson, Stephen R.; Granskog, Mats A.; Gerland, Sebastian; Sundfjord, Arild; Steen, Harald; Hop, Haakon; Cohen, Lana; Peterson, Algot Kristoffer; Jeffery, Nicole; Elliott, Scott M.; Hunke, Elizabeth Clare; Turner, Adrian K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-11)
      Large changes in the sea ice regime of the Arctic Ocean have occurred over the last decades justifying the development of models to forecast sea ice physics and biogeochemistry. The main goal of this study is to evaluate the performance of the Los Alamos Sea Ice Model (CICE) to simulate physical and biogeochemical properties at time scales of a few weeks and to use the model to analyze ice algal ...
    • The seeding of ice algal blooms in Arctic pack ice: The multiyear ice seed repository hypothesis 

      Olsen, Lasse Mork; Laney, Samuel R.; Duarte, Pedro; Kauko, Hanna M.; Fernández-Méndez, Mar; Mundy, Christopher John; Rösel, Anja; Meyer, Amelie; Itkin, Polona; Cohen, Lana; Peeken, Ilka; Tatarek, Agnieszka; Róźańska-Pluta, Magdalena; Wiktor, Josef; Taskjelle, Torbjørn; Pavlov, Alexey; Hudson, Stephen R.; Granskog, Mats A.; Hop, Haakon; Assmy, Philipp (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-03)
      During the Norwegian young sea ICE expedition (N-ICE2015) from January to June 2015 the pack ice in the Arctic Ocean north of Svalbard was studied during four drifts between 83° and 80°N. This pack ice consisted of a mix of second year, fi rst year, and young ice. The physical properties and ice algal community composition was investigated in the three different ice types during the ...
    • From polar night to midnight sun: Diel vertical migration, metabolism and biogeochemical role of zooplankton in a high Arctic fjord (Kongsfjorden, Svalbard) 

      Darnis, Gérald; Hobbs, Laura; Geoffroy, Maxime; Grenvald, Julie Cornelius; Renaud, Paul; Berge, Jørgen; Cottier, Finlo Robert; Kristiansen, Svein; Daase, Malin; Søreide, Janne; Wold, Anette; Morata, Nathalie; Gabrielsen, Tove M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-24)
      Zooplankton vertical migration enhances the efficiency of the ocean biological pump by translocating carbon (C) and nitrogen (N) below the mixed layer through respiration and excretion at depth. We measured C and N active transport due to diel vertical migration (DVM) in a Svalbard fjord at 79°N. Multifrequency analysis of backscatter data from an Acoustic Zooplankton Fish Profiler moored from January ...
    • Shared predation and its impact on two sympatric rodent species. Adding to nature’s complexity 

      Moen, Anthine (Master thesis; Mastergradsoppgave, 2017-09-03)
      I used a theoretical model with different predatory preference relationships but with no direct competition. Simulated time series were statistically analysed to evaluate changes in rodent dynamics, with respect to periodicity, synchrony, amplitude and symmetry. The study found that shared predation could mediate a relationship between the two rodents to some extent. Periodicity increased on average ...
    • Using food web structure based on stable nitrogen and carbon isotopes to investigate pelagic-benthic coupling in different areas of the Barents Sea 

      Tillman, Ann Mikaela (Master thesis; Mastergradsoppgave, 2017-11-15)
      Pelagic-benthic coupling is generally assumed to be tighter on Arctic shelves than in lower latitudes, due to for example pronounced seasonal cycles of sunlight and primary production and a potential mismatch between the bloom and its pelagic consumers. Pelagic-benthic coupling is also often stronger in shallower areas compared to deeper areas, due to the shorter distance between the productive, ...
    • Ungulate population monitoring in an open tundra landscape: distance sampling versus total counts 

      Le Moullec, Mathilde; Pedersen, Åshild Ønvik; Yoccoz, Nigel Gilles; Aanes, Ronny; Tufto, Jarle; Hansen, Brage Bremset (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-27)
      Researchers and wildlife managers strive for low bias and high precision (i.e. high accuracy) when estimating animal population sizes. Distance sampling is currently one of the most widely used monitoring methods. However, it relies on strict sampling designs and modeling assumptions that can be difficult to meet in the field. Here, we use data from two sub-populations of non-migratory wild Svalbard ...
    • SBMLmod: a Python-based web application and web service for efficient data integration and model simulation 

      Schäuble, Sascha; Stavrum, Anne-Kristin; Bockwoldt, Mathias; Puntervoll, Pål; Heiland, Ines (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-24)
      BACKGROUND: Systems Biology Markup Language (SBML) is the standard model representation and description language in systems biology. Enriching and analysing systems biology models by integrating the multitude of available data, increases the predictive power of these models. This may be a daunting task, which commonly requires bioinformatic competence and scripting. <br>RESULTS: We present ...
    • Brucellosis in livestock and wildlife: zoonotic diseases without pandemic potential in need of innovative one health approaches 

      Godfroid, Jacques (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-11)
      Human brucellosis remains the commonest zoonotic disease worldwide with more than 500 000 new cases annually. Understanding the biology of Brucella infections and the transmission patterns at the wildlife/livestock/human interface is of paramount importance before implementing any brucellosis control or eradication program in animals, even more so should interventions be justified within One ...
    • Imported human brucellosis in Belgium: Bio and molecular typing of bacterial isolates, 1996-2015 

      Mambres, Delphine Hanot; Boarbi, Samira; Michel, Patrick; Bouker, Nora; Escobar-Calle, Luisa; Desqueper, Damien; Fancello, Tiziano; Van Esbroeck, Marjan; Godfroid, Jacques; Fretin, David; Mori, Marcella (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-06)
      The aim of this study was to characterize by classical biotyping and Multi-Locus variable number tandem repeats (VNTR) Analysis (MLVA) all Brucella spp. derived from human cases in Belgium from 1996 to 2015. Final goals were to determine the species and biovar, to trace-back on genetic grounds the origin of each strain when patient history and risk factors were missing, and to survey for particular ...